CVE-2021-21369 : Exploit Details and Defense Strategies

Hyperledger Besu is an open-source, MainNet compatible, Ethereum client written in Java. A vulnerability in Besu versions prior to 1.5.1 allows for a denial-of-service attack involving the HTTP JSON-RPC API service. If username and password authentication is enabled for this service, a single user can overload the login endpoint, potentially causing valid requests to fail. This issue has been addressed in version 1.5.1.

Understanding CVE-2021-21369

This section provides insights into the nature and impact of the CVE-2021-21369 vulnerability.

What is CVE-2021-21369?

CVE-2021-21369 is a potential denial-of-service vulnerability in Hyperledger Besu versions prior to 1.5.1, affecting the HTTP JSON-RPC API service.

The Impact of CVE-2021-21369

The vulnerability allows a single user to overwhelm the login endpoint with invalid requests, impacting the processing of valid requests and potentially leading to a denial-of-service situation.

Technical Details of CVE-2021-21369

This section delves into the specifics of the vulnerability and its implications.

Vulnerability Description

The vulnerability in Besu versions before 1.5.1 revolves around the HTTP JSON-RPC API service, where an attacker with valid credentials can disrupt the normal operation by overloading the login endpoint with invalid requests.

Affected Systems and Versions

Hyperledger Besu versions prior to 1.5.1 are affected by this vulnerability.

Exploitation Mechanism

The vulnerability can be exploited by an authenticated user sending a large number of incorrect password requests, causing delays in password validation on the main vertx event loop.

Mitigation and Prevention

This section outlines steps to mitigate and prevent the exploitation of CVE-2021-21369.

Immediate Steps to Take

Users are advised to update their Hyperledger Besu installations to version 1.5.1 or later to mitigate the vulnerability.

Long-Term Security Practices

Implement a strong password policy and monitor API traffic to detect any unusual patterns that might indicate a denial-of-service attack.

Patching and Updates

Regularly check for security updates and apply patches provided by Hyperledger to address known vulnerabilities.